The present invention relates to an absorbent article that includes an effective liquid barrier, an element that can be used as a liquid barrier in an absorbent article, and a method of producing liquid barriers in absorbent articles.
An absorbent article includes, among other things, a bottom liquid-impermeable sheet, an absorbent layer or sheet disposed on said bottom sheet, and a top surface sheet which is intended to lie proximal to the wearer in use. When the absorbent article is a diaper or an incontinence guard, it will also include flexible side-flaps which extend laterally beyond the absorbent body on opposite sides thereof and elastic devices that extend longitudinally along the free side-edges of the side flaps at least within that part which is intended to form the crotch part of the article in use, said flaps and elastic devices enabling the absorbent article to be fitted to the wearer. The elastic devices function as leg elastic when the article is worn and are intended to seal around the wearer""s thighs and also to shape the article. The flexible side-flaps form tightening or sealing edges and have the additional function of preventing liquid, and possibly faeces, from leaking out at the edges, in other words they form barriers.
As an added safeguard against the leakage of liquid from the side-edges of an article, a number of absorbent articles also include additional, inner liquid-barriers or cuffs fastened in the proximity of the longitudinal edges of the article concerned. The purpose of the liquid barrier is to prevent liquid from escaping at the edges of the absorbent article and also possibly to prevent the escape of solids, such as faeces. This second barrier is placed inwardly of the leg elastic, i.e. inwardly of the outer liquid barrier, and is comprised of an essentially liquid-impermeable material, for instance a nonwoven material, and also of elastic devices which gather together, or pucker, the edge of the liquid barrier in abutment with the wearer. The unresilient, inelastic material is secured along one longitudinally extending edge thereof to the absorbent article near or at the longitudinally extending edges. The elastic device, e.g. elastic thread, is fastened along the other edge of the inelastic material, so as to gather together the liquid carrier and form a puckered edge which is partially extended or stretched when the article is donned. The puckered edge is usually formed by folding the inelastic material around one or more elastic threads, into a channel along the edge of the material. The inelastic material is glued or welded around the elastic threads. When the absorbent article is donned, the puckered edge lifts and is partially stretched, the extent of this stretch being dependent on the size of the wearer. Examples of diapers that include liquid barriers are found in SE-T3-0 264 238 and GB-A-2 188 532, for instance.
In the case of diapers that include liquid barriers or cuffs for instance, the barrier will be positioned so as to lie against the crotch and buttocks of the wearer and should prevent leakage in these areas. Each urine discharge will deliver a certain volume of liquid to the article. Because of the delay before this urine is able to penetrate through the upper sheet and be absorbed in the absorbent layer, a certain amount of urine will xe2x80x9cfloatxe2x80x9d in the absorbent article on top of the surface sheet. The barrier is intended to prevent this volume of urine from forcing its way out at the edges of the absorbent article. Cuffs can also be used on sanitary napkins, for instance.
It has been found, however, that this barrier is not leakage-proof.
The object of the present invention is to provide an improved liquid barrier that includes a more effective sealing edge and, at the same time, a softer and more comfortable edge in abutment with the wearer. A further object of the invention is to provide an absorbent article that includes at least one such barrier.
The invention relates to an absorbent article, such as a diaper, sanitary napkin, incontinence guard or like article, that includes longitudinally extending and transversely extending edges, a bottom liquid-impermeable sheet, an absorbent sheet or layer, a top liquid-permeable sheet which is intended to lie proximal to a wearer in use, and on each side of the centre line of the top sheet at least one longitudinally extending liquid barrier which is comprised of a longitudinally extending, essentially inelastic and essentially liquid-impermeable material that has two longitudinally extending edges, of which the first edge is fastened to the top liquid-permeable sheet or to the bottom liquid-impermeable sheet of the absorbent article along or adjacent to the longitudinal edge of said article, and the other edge of which is fastened to an elongated, prestretched elastic element to form a puckered, stretchable barrier edge that is intended to lie against the wearer of the article, wherein the elastic element is comprised of a band-like or ribbon-like elastic device or means having a first and a second longitudinally extending edge of which at least the first edge is fastened in a stretched state to the second edge of the essentially inelastic material such that the mutually joined edges will form a stretchable puckered first barrier edge, and including a longitudinally extending free part that forms a stretchable, essentially smooth second barrier edge, the elastic device being fastened to the essentially inelastic material in a manner such that when the article is donned said elastic device will lie against the wearer with the free part facing towards the centre line of the article and the gathered barrier edge facing outwards from the centre line of said article.
The invention also relates to an absorbent article which includes a liquid-impermeable sheet that is intended to lie against a wearer and is provided with elastic for shaping the article to the wearer""s body, said sheet including an aperture which is intended to be caused to register with the anus and urethra orifice of the wearer and around which aperture a stretchable sealing edge is disposed in the essentially liquid-impermeable sheet, which edge has been puckered by a prestretched elastic element, an absorbent body being disposed on that side of the essentially liquid-impermeable sheet that lies distal to the wearer in use, the absorbent body being enclosed between a liquid-permeable sheet on that side which lies proximal to the wearer in use, and a liquid-impermeable sheet, the elastic element being comprised of a band-like elastic device having a first and a second longitudinally extending edge of which at least the first edge is fastened in a prestretched state to the essentially liquid-impermeable sheet in the sealing edge such that the puckered edges form a stretchable, puckered first barrier edge, and including a longitudinally extending free edge which forms a stretchable, essentially smooth second barrier edge, the elastic device being fastened to the liquidimpermeable sheet such that when the article is donned, the elastic device will lie against the wearer with said free part facing inwardly towards said aperture and with the gathered barrier edge facing outwardly from said aperture.
The invention also relates to a web-like element for use as a liquid barrier in an absorbent article, said element including an elongated, essentially inelastic and essentially liquid-impermeable material having two longitudinally extending edges of which the first edge is free and intended to be fastened to the absorbent article and the second edge is fastened to an elongated, stretched elastic element so as to form a puckered, stretchable barrier edge, the elastic element being comprised of a band-like elastic device having a first and a second longitudinally extending edge of which at least the first edge is fastened in a stretched state to the second edge of the essentially inelastic material such that the mutually joined edges will form a stretchable, puckered first barrier edge, and including a longitudinally extending free part that forms a stretchable, essentially smooth second barrier edge. Thus, the web-like element comprises three barrier edges, i.e. the stretchable, puckered first barrier edge, the stretchable, essentially smooth second barrier edge and a third barrier edge consisting of the first edge of the essentially inelastic and essentially liquid-impermeable material, where the first and second barrier edges in a relaxed state are shorter than the third edge and can be stretched to the length of said third edge.
When the barrier element is stretched, e.g. when an absorbent article including such an element is donned, the two stretchable barrier edges will lie generally at right angles to the inelastic material, so that the barrier element obtains a T-shape.
The second edge of the elastic device conveniently forms said free part. However, the elastic device may be folded lengthwise and the first and second edges both fastened to the second edge of the inelastic material. The folded edge of the elastic device will then form said free part.
The second edge of the elongated, inelastic material is preferably folded to form a channel around at least the stretched first edge of the elastic device. The channel is fastened to the elastic device, e.g. glued or welded thereto, and forms the puckered barrier edge. It is also possible to insert and fasten both edges of the elastic device in said channel.
Nonwoven material, e.g. a multi-layer nonwoven material, is an example of the essentially inelastic material that can be used. Such a material may be an SMS material, i.e. spunbond-meltblown-spunbond.
The elastic device may comprise elastic film or elastic ribbon based on styrene block copolymers, such as SBS (styrene-butadien-styrene), SIS (styrene-isoprenestyrene), SEBS (styrene-ethylene-butylene-styrene) or SEPS (styrene-ethylenepropylene-styrene). The film may consist of several layers and may, for instance, be a three-ply film where the outer layers consist of polypropylene. The polypropylene functions to facilitate fastening of the film to the inelastic material and may, e.g., facilitate gluing to the other material. Polypropylene also feels more comfortable to the skin than a number of other elastic films, which feel like plastic against the skin, which one wishes to avoid. Elastic nonwoven material may also be used as the elastic devices.
An inventive barrier element is produced by laying the band-like elastic device against the web-like, essentially inelastic and essentially liquid-impermeable material with its first edge stretched and parallel with and close to the second edge of the inelastic material and with its second edge facing towards the first edge of said inelastic material. The first edge of the elastic device is joined to the inelastic material, for instance, glued or welded to the inelastic material, optionally after having folded the second edge of the inelastic material around the first edge of the band-like elastic device so as to form from the mutually joined parts a stretchable, puckered first barrier edge. The second edge of the elastic device will be free and form a stretchable, essentially smooth second barrier edge. The barrier element is incorporated in an absorbent article, by fastening the first edge of said barrier element to the top liquid-permeable sheet of the article, close to the longitudinally extending edge, or to the bottom liquid-impermeable sheet at the edge part of said article, said barrier element being turned so that the free edge or part of said elastic device faces towards the longitudinal centre line of the article.
When manufacturing an inventive absorbent article, the first edge of the web-like essentially inelastic and essentially liquid-impermeable material may be fastened to the top liquid-permeable sheet of the article close to said longitudinally extending edge, or to the bottom liquid-impermeable sheet at the edge of the article prior to forming the puckered barrier edge in accordance with the afore going. The elastic device will suitably have a width of at least 0.5 cm, preferably at least 1.0 cm. The width of the elastic device is preferably smaller than 5 cm.